1. Field of the Invention
The present invention relates in general to vehicle control. More particularly, in accordance with the present invention, indicator lines on a road, such as lane dividing lines, are detected and analyzed to collect information from which a current vehicle position is determined and parameters are developed to be considered in vehicle control.
2. Description of the Prior Art
Recent navigation systems, mounted on a vehicle, induce the driver to drive along a predetermined drive route. Japanese patent publication No. 6-58141 discloses a vehicle control system that controls the transmission or other system on the vehicle in accordance with the road data stored in the navigation system. In the prior art vehicle control, the road data for a vicinity around the current position is read out from a memory in the navigation system. However, when the vehicle enters a junction at which a road branches off from the main road, the prior art is not capable of determining if the vehicle is still on the main road or on the branch road. Such a situation could occur, for example, when the vehicle enters a ramp onto a speedway or an exit branched off from the main road at an interchange. In the prior art, such an occurrence could not be confirmed until the vehicle had moved too far away from a main road which is detected by GPS (global positioning system) or other current position sensor means. The mode or manner of vehicle control, such as automatic transmission control, should preferably differ between travel on the main road and on a branch road. Delay in detection of road change results in failure of appropriate vehicle control to be executed immediately after the vehicle has entered a branch road.
In the prior art, a drive route from a current position to a goal is determined only when the goal is input by the driver. Input must be done every time the goal is changed. This is sometimes troublesome and it is desirable to infer a drive route even if no goal is input by the driver.
When the vehicle is running on a multi-lane road, it has been impossible to determine the lane in which the vehicle is currently traveling. If the lane can be determined, for example if it can be determined that the vehicle is running in a passing lane on the speedway at a position astern of the junction at a predetermined distance, it could be inferred that the vehicle is most likely to go straight. As can be understood from this example, the result of determination of the driving direction at a junction becomes much more reliable by taking the lane position into consideration.
Accordingly, it is a principal object of the present invention to provide a vehicle control system which incorporates determination of the specific lane in which the vehicle is currently running.
In accordance with an aspect of the present invention, there is provided a vehicle control system comprising memory means storing road data; current position sensor means for detecting a current position of a vehicle; line recognizing means for recognizing indicator lines on a road; drive position determining means for determining the vehicle position with respect to the indicator lines; and control means for control of operation of at least one system mounted in the vehicle in accordance with the road data stored in the memory means and the result obtained by the drive position determining means.
The line recognizing means preferably includes a camera for taking a picture of the road ahead of the vehicle.
In a preferred embodiment, the drive position determining means comprises lane width change detecting means for detecting the distance between two indicator lines in the picture taken by the camera, the two indicator lines being located at opposite sides of a lane in which the vehicle is running, and branch determining means for determining the direction of movement of the vehicle at a branch in the road, in accordance with detection by the lane width change detecting means.
In another preferred embodiment, the drive position determining means comprises line width change detecting means for detecting the width of at least one indicator line in the picture taken by the camera, the indicator line being located at one or both of opposite sides of a lane in which the vehicle is traveling, and branch determining means for determining the direction of movement of the vehicle at a branch in the road in accordance with the result of detection by the line width change detecting means.
In the most preferred embodiment, the drive position determining means comprises lane width change detecting means for detecting the distance between two indicator lines in the picture taken by the camera, the two lines being located at opposite sides of a lane in which the vehicle is running, line width change detecting means for detecting the width of at least one of the two indicator lines, and branch determining means for determining the direction of movement of the vehicle at a branch in the road in accordance with the results of detection by the lane width change detecting means and the line width change detection means.
The drive position determining means may comprise lane continuity detecting means for detecting continuity of at least one indicator line in the picture taken by the camera to determine if the indicator line is solid or broken, the indicator line being located at one or both of opposite sides of a lane on which the vehicle is traveling, and drive lane determining means for determining the current driving lane of the vehicle in accordance with the result of detection by the lane continuity detecting means.
Alternatively, the drive position determining means may comprise line shift detecting means for detecting that an indicator line has gradually moved from one side to the other side in the picture taken by the camera, and lane change determining means for determining that the vehicle has changed lanes when a line shift is detected by the line shift detecting means.
The vehicle control system of the present invention preferably also includes reliability determining means for determining a reliability level with respect to the drive position that has been determined by the drive position determining means. The control means operates in a manner which differs depending upon the reliability level determined by the reliability determining means. In an example, the reliability determining means determines a reliability level in accordance with a plurality of results of determination by the drive position determining means that have been obtained within a predetermined period of time.
In a preferred embodiment, the reliability determining means determines a reliability level in accordance with a first drive position determined by the drive position determining means and a second drive position determined within a predetermined period of time by the drive position determining means.
The control means preferably operates, in a usual manner, depending upon the road data for a first drive route inferred by the current position detected by the current position sensor means, but is made operative in accordance with the road data of a second drive route when the second drive route is determined to be different from the first drive route by the drive position determining means.
The vehicle control system may further comprise decelerating operation sensor means for detecting initiation of a decelerating operation. In this case, the reliability level may be determined by the reliability level determining means in further consideration of detection of some decelerating operation by the decelerating operation sensor means.
The vehicle control system may further comprise decelerating operation sensor means for detecting that some decelerating operation has been initiated, in which case the control means is made operative in response.
The decelerating operation is preferably at least one selected from the group consisting of operation of a foot brake pedal, release of an accelerator pedal, operation of a trafficator and rotation of a steering wheel beyond a predetermined angle.
In a typical embodiment, the control means controls a shift range of speeds or gear ratios in an automatic transmission.
In accordance with another aspect of the present invention, there is provided a method of vehicle control comprising the steps of taking a picture of a road ahead of a current vehicle position, including indicator lines extending on the road; determining a current vehicle position with respect to the indicator lines; obtaining road data of a drive route to be determined by the current vehicle position; and controlling operation of a system mounted on the vehicle in accordance with the road data. Determination of the current vehicle position is carried out by at least one or any combination of results of drive lane determination that determines the current driving lane of the vehicle on a multi-lane road in accordance with detection of solid or broken lane divider line, branch determination that determines if the vehicle has entered a junction on the road in accordance with detection of change of profile of the indicator lines, and lane change determination that determines a lane change of the vehicle at the junction in accordance with detection of lateral movement of the indicator (lane) lines in the picture.
In accordance with still another aspect of the present invention, there is provided a computer readable memory media to be used in combination with a computer mounted on a vehicle. The memory media of the present invention stores a program by which the computer controls operation of the vehicle in accordance with a method comprising the steps of taking a picture of a road ahead of a current vehicle position including indicator lines extending on the road; determining a current vehicle position with respect to the indicator lines; obtaining road data of a drive route to be determined by the current vehicle position; and controlling operation of a system mounted on the vehicle depending upon the road data. Determination of the current vehicle position should be carried out by at least one or any combination of results of drive lane determination that determines a current drive lane of the vehicle on a multi-lane road depending upon detection of the type of the indicator lines, i.e., solid or broken, branch determination that determines if the vehicle enters a junction on the road depending upon detection of change of profile of the indicator lines and lane change determination that determines a lane change of the vehicle at the junction depending upon detection of lateral movement of the indicator lines in the picture.